GEOLOGY civil engineering reportreport.pptx



from the viewer, the smaller is the size of the object. Relative size is supported by the concept of linear perspective. Parallel lines that meet at the horizon give the illusion of distance. Objects, therefore, become smaller the nearer they are to the point in the horizon where the two lines converge.
Atmospheric Perspective. This is also known as aerial perspective. The illusion of depth is created by techniques known as gradient (a gradual change). This may be a gradient in texture, brightness, color intensity, and combination of warm and cool colors. To understand gradient better, the picture plane is divided into three parts: the lower part is the foreground, which is nearest to the viewer, the second is the middle ground, and the upper part of the picture plane is the background. In applying gradient to give the illusion of depth, objects in the foreground would be bigger, detailed, and brighter. As the eye moves to the middle ground, the objects' appearance would gradually change. In the middle ground objects would be smaller compared with those in the foreground. There would be less detail, and colors are not so bright. When the viewer looks at the background, objects will be smaller, they will have very little detail, and the colors are hazy giving the illusion of distance.

1. Modes of Rock slope Failures

2. INTRODUCTION Rock failure modes are important information as it helps recognize the adequacy of the support designed on the basis of the nature of an engineering work. Failure of rock is an important problem arising during underground construction of shafts, tunnels etc.

3. EXAMPLE

4. In a failure mode , the rock block slides on a single face that can be a joint plane or bedding plane striking parallel to the slope face and dipping into free space/excavation at an angle greater than the angle of internal friction of the joint/bedding material.

5. Modes of failure in soft weathered or jointed rock masses These include : Modes of Failure in rocks They are common in soft formations such as shale and in deeply weathered, jointed or broken rock masses. Slumping or sliding Raveling -granular disintegration into small components by different processes.

6. Modes of Failure in Hard Rocks Wedge sliding Movement of a block along two planes of weakness. There are line of intersection and lateral block release. Typical Materials: Blocky rocks with at least two continuous and nonparallel joint sets, e.g. cross jointed sedimentary rocks, regularly faulted rocks, block-jointed granite and especially foliated or jointed metamorphic rocks

7. Plane sliding Movement of a block along a plane weakness. There are plane of weakness, lateral block release through joints, topography, excavation, or intact rock failure Typical Materials : Hard or soft rocks with well-defined discontinuities and jointing, e.g. layered sedimentary rocks, volcanic flow rocks, block-jointed granite, foliated metamorphic rocks

8. Circular failure One of the most probable instabilities on slopes with severely crushed rock or soil slopes. Typical Materials: Heavily jointed and weathered rock masses similar to the soils.

9. Toppling Overturning of rock layers inclined steeply into the hillside. A mechanism is needed to start the process of toppling such as erosion, exaction at the toe of the slope Typical Materials: Hard rocks with regular, parallel joints dipping away from the free space/ excavation, i.e. dipping into the hillside, with or without crossing joints; foliated metamorphic rocks and steeply dipping layered sedimentary rocks; also in block-jointed granites

10. Most commonly used laboratory test to investigate mechanical properties of intact rocks. -here the lenght-to-diameter ration of samples should be on the order of two F-maximum applied load A-specimen cross sectional area If the lenght-to diameter ratio of samples are not in the order of two. Use eqn 2. 1. Uniaxial test Tests applied on rocks 1. 2.

11. 2. Brazilian test -is a geotechnical laboratory test for indirect method of assessing the tensile strength of rocks, based on observation that most rocks in biaxial stress fields fail when one principal stress is compressive. -a disc shape specimen of the rock is loaded by two opposing normal strip loads at the disc periphery. The specimen diameter shall preferably be not less than 54mm or atleast 10 times the average grain size. Thickness should be 0.5mm-0.6mm ,loading may from 10-50 kN /min. where: F-applied load D-diameter of the sample(D =2r) L-thickness of the sample

12. 3. Point Load test Used as an efficient and applicable method to rock classification. Based on this method failure of rock is occurred due to tensile stress. -also cost effective alternative method to indirectly obtain universal compressive stress and can be conducted on rock samples without using any special sample preparation.

13. References https://www.sciencedirect.com ASTM(Standard Test Method D3967-81 International Rock Mechanics *lecture Civilblog.org Link.springer.com Researchgate.net Rock Mechanics An Introduction(2013); Naaratnam,Sanjay,braja

14. THANK YOU FOR LISTENING!!! ANY QUESTIONS 🤔🤔🤔🤔